The sterilization of packaging material within the food packaging sector is of fundamental interest for guaranteeing the needed shelf life of the packaged food products and, accordingly, the safety of the consumers. This is even more important when food products are packaged under aseptic conditions.
It is known in the art to fill any type of pourable food product such as carbonated liquids (e.g. sparkling water, soft drinks and beer), non-carbonated liquids (including still water, juices, teas, sport drinks, wine, etc) and beverages containing pulps into receptacles, such as containers, vessels, jars and bottles made of base components, like glass, plastics, aluminum, steel, and composites.
In general, the receptacles prior to being filled with the pourable product are sterilized within a receptacle sterilization apparatus and are subsequently filled with the desired pourable product within a filling apparatus.
After the filling of the receptacles, typically the respective pourable product inlets/outlets are sealed by the application and fastening of respective receptacle closures.
Prior to the application of the receptacle closures, the receptacle closures must be sterilized within a respective sterilization apparatus. After sterilization the sterile receptacle closures are fed to a capping device being integrated within the filling apparatus or being separated from the filling apparatus by a filled receptacle conveyor.
Receptacle closures may be of the type known as caps, screw caps, sports caps, stoppers etc., and they may be produced from a variety of materials such as plastics and metal. It is further known that the receptacle closures can vary in format.
In the following, we limit the description to the specific example of plastic screw caps. However, it must be clear that the present invention may be also used to particular advantage for any other type of receptacle closures such as caps, sports caps and others made also from materials different than plastic, such as metal.
A sterilization apparatus for the sterilization of receptacle closures of the same applicant is known from the European patent document EP-B-2318054.
The sterilization apparatus disclosed in EP-B-2318054 comprises a guide rail housed within a treatment chamber designed to receive receptacle closures at an inlet station and to guide the receptacle closures to an outlet station from where the receptacle closures are fed to a capping device.
The sterilization apparatus further comprises a sterilization device having an injection tube arranged below a portion of the guide rail and is adapted to inject a heated and vaporized sterilization agent, in particular heated and vaporized hydrogen peroxide. In particular, one end of the injection tube is arranged in the vicinity of the inlet station and the other end of the injection tube is placed at an intermediate station between the inlet station and the outlet station.
The injection tube has a plurality of injection holes arranged over its complete extension in such that by injection of the heated and vaporized sterilization agent a cloud of sterilization agent is formed within an injection zone of the treatment chamber. In particular, the longitudinal extension of the injection zone is defined by the longitudinal extension of the injection tube.
The sterilization apparatus also comprises a drying device adapted to direct heat air to the receptacle closures in the vicinity of the outlet station for drying off sterilization agent residues from the receptacle closures prior to exiting from the treatment chamber.
The sterilization apparatus disclosed also comprises an exhaust extraction device configured to capture by means of a draught effect, in use, exhaust molecules from the treatment chamber through a plurality of respective exhaust openings. The exhaust extraction device further comprises a plurality of extraction hoods, each associated to one respective exhaust opening. Furthermore, each exhaust hood has flange members for adjusting the effective cross-section of the exhaust hood itself. The adjustment of the effective cross-sections is required for providing on the one hand for the needed exhaust extraction efficiency of the exhaust extraction device and on the other hand to limit the disturbance of the stability of the treatment environment, in particular the cloud of sterilization agent within the injection zone.
One drawback of the sterilization apparatus disclosed in EP-B-2318054 is that the exhaust extraction device requires a sensitive control of the adjustment of the function of the exhaust extraction device comprising the adjustment of the flanges of the exhaust hoods for guaranteeing the stability of the cloud of sterilization agent and, therewith, the quality of the sterilization process.
Furthermore, the disclosure of EP-B-2318054 illustrates that the guide rail guides receptacle closures of only one type/format of receptacle closures. Thus, in case of a change to types/formats of receptacle closures not supported by the guide rail extensive and time consuming changes need to be performed to adapt the sterilization apparatus to the new closure format.